Steve King, apparently, isn't conservative enough for the Club for Growth.

He may be a tea party firebrand and, traditionally, one of the most conservative members of the House, but Club for Growth says that on votes they scored, King was wrong 29 percent of the time in 2013.

The Iowa Republican has a 91 percent lifetime score with Club for Growth, and he was actually endorsed by the Club in his 2012 race. But, this year, King ranked right in the middle of Republicans with a 71 percent score. That's well short of the 90 percent threshold needed to win the group's "Defender of Economic Freedom" award. What happened?

The easy explanation, in two words? "Farm" and "bill."

According to CQ Roll Call's math, King lost about 15 percentage points over votes related to the farm bill. There were 87 possible points for a legislator this year in the Club for Growth scorecard, and King lost 13 of them with the farm bill: seven points for voting for the June farm bill, three points for the farm-only measure, two points for voting against a Paul Broun, R-Ga., amendment to repeal the permanent price support for milk, and one point for voting against a Steve Chabot, R-Ohio, amendment to eliminate the Market Access Program, which helps promote U.S. agricultural products.

Club for Growth — and Heritage Action for America, which has their own scorecard — hated the farm bill, and a healthy number of votes were related to the legislation. King did pick up some Club for Growth points on the farm bill for supporting a Tim Huelskamp, R-Kan., amendment to implement food stamp restrictions on able-bodied adults, as well as an amendment from the erstwhile-Rep. Trey Radel, R-Fla., to eliminate a $10 million annual authorization for a National Sheep Industry Improvement Center.

But King did dissent on some other Club for Growth votes. Namely, King voted for a flood insurance amendment from Bill Cassidy, R-La., that grandfathered National Flood Insurance Program rates, and he voted for the flood insurance program, which Club for Growth opposed. He also voted for a continuing resolution in September that would have delayed Obamacare for a year. (The Club for Growth thought that plan was too liberal.)

King also took a hit on two amendments from California Republican Tom McClintock.

McClintock, who had a 100 percent rating with the Club for Growth this year, came to Congress in 2009 with the club helping him defeat former Congressman Doug Ose in a Republican primary, and Democrat Charlie Brown in the general election. McClintock beat Brown by less than 2,000 votes in 2008.

Ever since then, McClintock has maintained a close relationship with the club.

The conservative group key voted a McClintock amendment on the Energy and Water Appropriations bill that would have cut funding for energy programs by $1.5 billion, as well as a McClintock amendment on the Transportation Appropriations bill that would have eliminated $100 million for the Essential Air Service program. King voted against both of those amendments.

Overall, King's 20 percent drop was among the largest GOP slides. Mississippi Republican Gregg Harper had a 41 percent score this year despite a 70 percent lifetime average, Majority Whip Kevin McCarthy of California, the No. 3 Republican in the House, went from a 78 percent lifetime score to a 53 percent score in 2013, and Rep. Tom Cole, R-Okla., went from a 70 percent lifetime score to a 49 percent score this year.

But King's decline seems particularly surprising, especially since he has a strongly partisan voting record. According to a yearly analysis by CQ Roll Call, King voted against President Barack Obama's position 89 percent of the time in 2013.

Updated 5:16 p.m. | Club for Growth spokesman Barney Keller contacted CQ Roll Call Monday night to let us know he felt the headline and lede of the story were disingenuous.

From Keller: “Our annual Congressional scorecard is designed to capture a lawmaker’s votes for one year. This year, Congressman King got a 71%. In previous years, he’s received in the 90s and has a lifetime score of 91%. If more people had lifetime scores of 91% the world would be a better place.”